DEFECT-ENGINEERED NI-MOF/NSP-DOPED BIOMASS CARBON HETEROSTRUCTURE FOR ULTRASENSITIVE NON-ENZYMATIC HYDROGEN PEROXIDE DETECTION

Hydrogen peroxide (H₂O₂) is an important reactive oxygen species whose abnormal levels are associated with oxidative stress, inflammation, cancer progression, and neurological disorders. The development of sustainable and highly sensitive non-enzymatic sensors for H₂O₂ monitoring remains a significant challenge. In this work, a defect-engineered Ni-MOF/NSP-doped orange peel activated carbon (Ni-MOF-NSP-OAC) heterostructure was developed for electrochemical H₂O₂ detection. NSP-doped activated carbon was synthesized from waste orange peel to provide a conductive, defect-rich support, followed by hydrothermal growth of a Ni-BDC metal-organic framework. Structural and morphological characterization confirmed the successful formation of the heterostructure and homogeneous distribution of active components. The synergistic interaction between the redox-active Ni sites and NSP-doped carbon facilitated efficient charge transfer and enhanced electrocatalytic activity toward H₂O₂ oxidation in alkaline medium. Differential pulse voltammetry revealed a wide linear detection range of 0.5–950 µM, high sensitivity of 16,550 µA mM⁻¹ cm⁻², and a low limit of detection of 0.33 µM. The sensor exhibited excellent selectivity against common interfering species. Practical applicability was demonstrated through recovery studies in milk and artificial sweat samples, yielding recoveries of 98.5–101.8% with relative standard deviations below 6.5%. These findings highlight the potential of sustainable MOF–biomass carbon heterostructures for advanced electrochemical sensing, food safety monitoring, wearable devices, and point-of-care diagnostics.